Terminal devices such as smartphones and tablet computers are typically provided with Universal Serial Bus (USB) receptacles. USB receptacles and compatible USB plugs are used to interface to a wide variety of equipment including, for example, laptop computers, printers, data acquisition equipment, cameras, flash memory drives, smartphones, feature phones, desktop computers, music players, game consoles and game controllers. A cable having USB plugs at both ends is used to facilitate connections between two different devices equipped with USB receptacles.
The latest iteration of the USB standard is called USB Type-C. The USB Type-C standard affords higher speed data transfer. The USB Type-C standard also includes a new horizontally and vertically symmetric connector design and a 180° rotationally symetric pin layout so that the connector can be inserted either of two ways, i.e., right-side-up or upside-down. Incidently a USB Type-C cable uses the same style of plug on both ends.
Among the pins defined in the USB Type-C standard is a Configuration Channel (CC) terminal pin. The CC terminal pin is used to detect insertion of plug (attached to a cable attached to another device) into a receptacle and for hand shaking. Per the USB Type-C standard a host device equipped with a USB Type-C receptacle periodically sends out a pulse on the CC terminal pin of the USB Type-C receptacle to probe for the presence of a connected plug. When a plug that is connected to a cable that is connected to a second device is inserted into the USB Type-C receptacle a USB Type-C controller in the second device will detect the pulse on the CC terminal pin and communication between the host device and the second device will be initiated.
Certain host devices that will include the USB Type-C receptacle will be designed to be waterproof However an issue arises if electricaly conductive liquid (e.g., juice, seawater) gets into and stays in a receptacle conforming to the USB Type-C standard. Over a long period of time, the aforementioned periodic pulse sent out on the CC terminal pin can drive an electrochemical corrosion reaction on pins of the receptacle. It has been confirmed experimentally that corrosion occurs if a USB Type-C is left operating for several days with water in it.
One way to address the corrosion problem would be to provide a water tight cap that goes over the receptacle. However it is somewhat inconvenient to remove and replace the cap and the cap can get lost.
It would be desirable to eliminate the problem of electrochemical corrosion driven by the CC terminal pulse signals.